Clarification Needed on Correcting 2024 & 2025 Excess HSA Contributions

Summary:

• I obtained health insurance through work in November 2024 and independently opened an HSA at Fidelity.
• I contributed the full 2024 HSA limit ($4,150) as a lump sum in December 2024 via the last-month rule.
• I contributed the full 2025 HSA limit ($4,300) as a lump sum in January 2025.
• I invested the entire balance, so my account has accrued investment gains. The HSA is currently a little over $10,000.

The issue:
Recently, I realized that my employer health plan was not actually HSA-eligible. Although it met the IRS deductible and out-of-pocket limits, it provides copays and other benefits before the deductible, and is a gold-tier plan. I should never have opened or contributed to an HSA.

Steps taken so far:
I called Fidelity and they directed me to submit a Return of Excess HSA Contributions form. However, the form only allows me to select 2025 from the drop-down menu as the year of excess contribution.

My understanding is that Fidelity would issue a Form 1099-SA in January 2026, showing the returned 2025 contribution plus earnings, and that the earnings portion is taxable as ordinary income.

My questions:

1. What do I do about the 2024 contribution (plus its earnings)? Fidelity’s form doesn’t allow me to select 2024, but that $4,150 also needs to be treated as excess for that year. It's my understanding that the IRS charges a 6% excise tax each year on excess contributions that remain in the HSA.
2. I’ve already liquidated the investments, so the entire HSA account is in cash. What is the correct method to remove the 2024 excess contribution and associated earnings? Do I simply transfer the remaining cash to my brokerage account or is there a specific way to ensure the distribution is classified correctly and not mistaken as a normal HSA withdrawal?
3. It's my understanding I will need to amend my 2024 tax return by removing by updating Form 8889 (zero out all HSA contributions) and Schedule 1, Line 13 (remove HSA deduction).